Apparatus for loading and packing material into sheaths



Dec. 21, 1943. 11 ASHTON 2,337,304

APPARATUS FOR LOADING AND PACKING MATERIAL INTO SHEATHS Filed March 27. 1942 T2121. Fig.2.

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His Attorney.

Patented Dec. 21, 1943 APPARATUS FOR LOADING AND PACKING MATERIAL INTO SHEATHS Herbert Toms Ashton, Davyhulme, near Manchester, England, assignor to General Electric Company, a. corporation of New York Application Marclr' 27, 1942, Serial No. 436,508 In Great Britain June 24, 1941 6 Claims.

This invention relates to apparatus for loading and packing material into a sheath, more particularly for loading pulverulent or powdered r comminuted material into a sheath, and it has for its object the provision of improved apparatus of this character.

While not limited thereto, this invention has special application in the manufacture of sheathed heater elements which comprise an electric resistance element embedded in a powdered, pulverulent or comminuted filling material, such for instance as magnesium oxide, within a tubular or like elongated sheath or encasement. It is generally essential and desirable for the filling material to be compacted as tightly aspossible and for the resistance element to be held truly concentric with the sheath throughout its length. In some cases, the filling material has been compacted by varying its volume by processing the material, while in other cases the compacting has been effected by swaging, drawing or rolling the sheath.

In addition to the manufacture of the heater element proper as above described, the problem of compacting the filling material is also present in connection with elements called cold ends; these are generally idle lengths attached to the end or ends of the heater element proper for facilitating the attachment and connection of the heater element in the desired position, or the attachment or connection of the heater in this position. These cold ends consist of a sheath, a conducting core of low resistance attached to the heater element, and the filling of suitable insulating material. generally of pulverulent, powdered or comminuted form.

In accordance with this invention, in one form thereof, the sheath is supported in an upright position, and the filling material is introduced into the sheath through the open upper end at a suitable regulated rate.

Arranged to operate within the sheath. is a suitable tamper which is adapted to be vibrated up and down so as to compact the filling material within the sheath as it is introduced therein.

The tamper is vibrated up and down within the sheath by suitable electromagnetic means. An operating member for the tamper is arranged outside of the sheath. One of the tamper or operating members is magnetizable while the other is constructed and arranged to generate magnetic fields at difierent points along the lengths of the sheath. A magnetic field is generated first to operate the tamper up in the sheath, and then a magnetic field is generated to operate it downwardly in the sheath, and this process is repeated so as to vibrate the tamper rapidly up and down in the sheath while the material is being fed into the sheath.

For a more complete understanding of this invention, reference should be had to the accompanying drawing in which Fig. 1 is a front elevation of sheath loading apparatus arranged in accordance with this invention, parts being shown in section so as to illustrate certain details of construction; Fig. 2 is a side elevation of the sheath loading apparatus shown in Fig. 1; Fig. 3 is an enlarged fragmentary sectional view illustrating certain electromagnetic elements used to control the tamper in the apparatus of Figs. 1 and 2; and Fig. 4 is a diagrammatic representation of the electromagnetic means of Fig. 3 and certain control elements therefor.

Referring to the drawing, this invention has been shown in one form as applied to apparatus for loading a sheathed heating element which has a resistance core 10, an outer sheath H and compacted electrically insulating and heat conducting material l2 within the sheath embedding the resistance element It! and holding it in spaced relation with reference to the sheath.

The loading apparatus comprises a suitable support 13 for holding the sheath in an upright position. Mounted upon the support [3 is a support I 4 for the lower end of the sheath II. As shown, the support M has an upright protuberance l5 which is received in the lower end of the sheath to hold the sheath from sidewise displacement with reference to the support. The support I 4 is also provided with a recess l6 for receiving the lower end of the resistance element Ill.

The upper end of the sheath is arranged to be held by a combined holding and feeding device I! which is provided with a depending tubular discharge section Ila. This section is provided with a countersunk lower end I 8 which is adapted to receive a reduced section l9 provided on the upper end of the sheath, as clearly shown in Fig. 1.

The support I for the lower end of the sheath is mounted upon a plunger 20 which is biased upwardly by means of a compression spring 2|. It will be understood that in mounting the core I0 and sheath II in the loading apparatus, the core will first be inserted upwardly through the support I1, and the upper end of th sheath II) will be inserted in the counterbore E8. The lower end of the sheath and core may then be mounted on the support [4 by depressing the support and then bringing the core into alignment with the recess l6 and the lower end of the sheath into position to receive the protuberance l5, after which the support 14 may be released so as to be pressed upwardly by means of the compression spring 2|. Thereafter, the sheath and core will be held upwardly by means of this spring.

As pointed out above, the member I! also func-, tions to feed the material [2 into the sheath. For this purpose it is provided at its upper end with a funnel or hopper section 22. The insulatin material is fed into the funnel or hopper from a suitable reservoir 23 which is provided at its lower end with a spout 24 discharging into the upper end of the funnel. The discharge of the material from the reservoir 23 through the,

spout 24 is controlled by means of a suitable valve (not shown). Theposition of this valve is controlled by means of a valve operating stem 25 to regulate the rate at which the material flows from the reservoir into the sheath.

A tamper 26 is mounted within the sheath 1 l, and is rapidly vibrated up and down to compact the insulating material as it is fed into the sheath; it also functions to hold the resistance element H! concentric with the sheath as the material is fed in. 1

The tamper is of such shape as to have some clearance with the bore of the sheath and also with the core l0. Preferably, the tamper will be of cylindrical form, the outside diameter of the tamper being somewhat less than the internal diameter of the sheath and will be provided with an axial bore 28 which receives the core, this bore having a diameter somewhat larger than the diameter of the core. The tamper is guided in its movement up and down in the sheath by means of a plurality of ribs 21 arranged longitudinally of the tamper and spaced at intervals circumferentially thereof. It will be observed that the insulating material which flows into the top can flow past the tamper into the lower part of the sheath through the passageways defined by the ribs 21, the body of the tamper, and the wall of the sheath.

The tamper is vibrated up and down in the sheath by means of electromagnetic action. In the specific embodiment of the example illustrated the tamper is formed of a magnetic material. Cooperating with the tamper are a pair of electromagnetic coils 29 and 38 arranged one above the other, as clearly shown in Fig. 3. These coils are wound upon two sections of a suitable electrically insulating supporting frame 3!. This frame in turn is supported by cables 32. In will be observed that the coils 29 and 3|] are arranged to encircle the sheath II.

The coils 29 and 30 are alternately excited to cause the tamper to be attracted first toward 7 one coil and then toward the other. In this way the tamper is first elevated in the sheath and then depressed so as to impart impacting blows to the material i2 and thereby compact it.

The coils may be energized from any suitable source of electrical supply 33, and are intermittently energized by means of a suitable commutator 34. The commutator is provided with a conducting section 35, and a pair of nonconducting sections 36. It is further provided with brushes 31, 38, 39, and 4 9 connected to the coils and supply source, as shown in Fig. 4. It will be observed that when the conducting section 35 of the commutator engages the opposite brushes 3! and 39 the coil 30 will be energized, whereas when the conducting section engages the brushes 38 and 40 the coil 29 will be energized.

The commutator will be driven by any suitable means at a substantially constant speed, and the rate of flow of the filling material into the sheath will be adjusted in relation to the periodicity of vibration of the tamper so that the additional material added by each blow of the tamper is appropriate for the degree of compacting desired.

The cables 32 pass over suitable pulleys 4| and 42 and the weight of the coils is counterbalanced by suitable weights 43 and 44 attached to the cables, as shown. The counterweights may be such as to elevate the coils at a suitable predetermined rate which will be determined by the rate at which the material I2 is fed into the sheath so that the mean level of the coils will gradually rise as the mean level of the tamper rises due to the rising level of the material in the sheath.

As an alternative, the weight of the coils may be substantially balanced and the magnetic attractive forces between the tamper and the coils used to gradually elevate the position of the coils; that is, as the mean level of the tamper rises due to the rising level of the material I2, the coils themselves will automatically rise with the tamper clue to the electromagnetic interaction between the tamper and the coils.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within the the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for filling a sheath with a material comprising means for holding said sheath in an upright fixed position, means for feeding said material into the upper end of said sheath, a tamper within said sheath for packing said material formed of a magnetic material and constructed and arranged so that the material fed into said sheath can fiow by the tamper to the lower end of said sheath, magnetic operating means constructed and arranged alternately to generate magnetic fields both to raise said tamper in said sheath and to lower it therein so as to compact said material in said sheath as it is fed in, and means for elevating said magnetic oper-. ating means as the level of the material in said sheath rises so that the mean position of said tamper rises with said level.

2. Apparatus for loading pulverulent material into a sheath comprising means for feeding said material into said sheath at a regulated rate, tamper member in said sheath for compacting said material and an operating member for said tamper outside of said sheath, one of said members being magnetizable and the other constructed and arranged alternately to generate a magnetic field at a point along the length of said sheath to attract said tamper away from the material in the sheath, and then at a point along said length to attract said tamper toward said material, whereby the tamper is reciprocated in said sheath to compact said material, and means for effecting relative movement between said sheath and said operating member so that the mean position of the reciprocating tamper is advanced with the level of the material in said sheath as the sheath becomes filled.

3. Apparatus for filling a sheath with a pulverulent material comprising means for holding said sheath in an upright fixed position, means for feeding said material into the upper end of said sheath at a regulated rate, a tamper within said sheath for compacting said material formed of a magnetic material and constructed and arranged so that the material fed into said sheath can flow by the tamper to the lower end of said sheath, an electromagnetic device outside of said sheath for generating magnetic fields, means controlling said electromagnetic device first to generate a field to force said tamper up in said sheath and then to generate a field to force said tamper down in said sheath in a series of cycles, whereby said tamper is vibrated up and down in said sheath to compact said insulating material therein, and means providing for movement of said electromagnetic device upwardly by its attractive force for said tamper as the level of material rises in said sheath.

4. Apparatus for filling a sheath with a pulverulent material comprising means for holding said sheath in an upright fixed position, means for feeding said material into the upper end of said sheath, 2. tamper within said sheath for packing said material formed of a magnetic material and constructed and arranged so that the material fed into said sheath can ilow by the tamper to the lower end of said sheath at a regulated rate, a pair of electromagnetic coils posttioned one above the other outside of said sheath and each when energized generating a magnetic field to attract said tamper to it, means for alternately energizing said coils so as to cause said tamper to vibrate up and down in said sheath, and means for elevating said coils along said sheath at a rate dependent upon the rate of fiow of said material into said sheath.

5. Apparatus for filling a sheath with a pulverulent material comprising means for holding said sheath in an upright fixed position, means for feeding said material into the upper end of said sheath, a tamper Within said sheath for.

packing said material formed of a magnetic material and constructed and arranged so that the material fed into said sheath can flow by the tamper to the lower end of said sheath at a regulated rate, a pair of electromagnetic coils positioned one above the other outside of said sheath and each when energized generating a magnetic field to attract said tamper to it, means for alternately energizing said coils so as to cause said tamper to vibrate up and down in said sheath, and means suspending said coils so that they are elevated at a regulated rate by the attractive force between them and said tamper as the level of the material in said sheath rises.

6. Apparatus for filling a sheath with a pulverulent material comprising means for holding said sheath in an upright fixed position, means for feeding said material into the upper end of said sheath, a tamper Within said sheath for packing said material formed of a magnetic material and constructed and arranged so that the material fed into said sheath can flow by the tamper to the lower end of said sheath at a regulated rate, a pair of electromagnetic coils positioned one above the other outside of said sheath each when energized generating a magnetic field to attract said tamper to it, means for alternately energizing said coils to cause said tamper to vibrate up and down in said sheath, and means for supporting and counterbalancing the weight of said coils so that they are elevated at a regulated rate as the level of the material in said sheath rises.

HERBERT TOMS ASHTON. 

